Picture frame



FIG. 1 is a bottom and left perspective view of a picture frame showing my new design;

FIG. 2 is a top and right perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a left side view thereof, the right side view being a mirror image; and,

FIG. 5 is a top view thereof, the bottom view being a mirror image.

The broken lines are for disclosure purposes only and do not form part of the claimed design. The back view does not form part of the claimed design. 

The ornamental design for a picture frame, as shown and described. 